Allow for bullet drag

src/Dodge/Particle/Bullet/HitEffect.hs

@@ -56,7 +56,7 @@ bulBounceArmCr' bt p cr w
     pOut = p +.+ 2 *.* newDir
     reflectVel = magV bulVel *.* newDir
     addBouncer = worldEvents %~ ( over particles (bouncer :) . )
-    bouncer = (aGenBulAt Nothing pOut reflectVel 
+    bouncer = (aGenBulAt Nothing pOut reflectVel (_btDrag bt)
                                       (_btHitEffect' bt) (_btWidth' bt)
               ) {_btTimer' = _btTimer' bt - 1}
 {- | Bullet pass through creatures.  -}
@@ -79,7 +79,7 @@ bulPenCr' bt p cr w
     sp = head $ _btTrail' bt
     ep = sp +.+ _btVel' bt
     addPiercer = over particles (piercer :)
-    piercer = (aGenBulAt (Just cid) p (_btVel' bt) 
+    piercer = (aGenBulAt (Just cid) p (_btVel' bt) (_btDrag bt)
                                       (_btHitEffect' bt) (_btWidth' bt)
               ) {_btTimer' = _btTimer' bt - 1}
 {- | Heavy bullet effects when hitting creature:
@@ -138,7 +138,7 @@ bulBounceWall bt p wl = damageWall (Blunt 50 sp p ep) wl . over worldEvents addB
     ep = sp +.+ _btVel' bt
     sp = head $ _btTrail' bt
     pOut = p +.+ squashNormalizeV (sp -.- p)
-    bouncer = (aGenBulAt Nothing pOut reflectVel (_btHitEffect' bt) (_btWidth' bt)
+    bouncer = (aGenBulAt Nothing pOut reflectVel 0.5 (_btHitEffect' bt) (_btWidth' bt)
               ) {_btTimer' = _btTimer' bt - 1}
     reflectVel = reflVelWall wl (_btVel' bt)
     addBouncer = ( over particles (bouncer : ) . )

src/Dodge/Particle/Bullet/Spawn.hs

@@ -16,13 +16,15 @@ aGenBulAt
     :: Maybe Int -- ^ Pass-through creature id
     -> Point2   -- ^ Start position
     -> Point2  -- ^ Velocity
+    -> Float   -- ^ Slowdown
     -> HitEffect 
     -> Float    -- ^ Bullet width
     -> Particle
-aGenBulAt maycid pos vel hiteff width = BulletPt
+aGenBulAt maycid pos vel drag hiteff width = BulletPt
     { _ptDraw = drawBul
     , _ptUpdate = mvBullet
-    , _btVel' = vel
+    , _btVel'   = vel
+    , _btDrag   = drag
     , _btColor' = V4 2 2 2 2
     , _btTrail' = [pos]
     , _btPassThrough' = maycid
@@ -35,13 +37,15 @@ aDelayedBulAt
     -> Maybe Int -- ^ Pass-through creature id
     -> Point2   -- ^ Start position
     -> Point2  -- ^ Velocity
+    -> Float    -- ^ Drag
     -> HitEffect 
     -> Float    -- ^ Bullet width
     -> Particle
-aDelayedBulAt vfact maycid pos vel hiteff width = BulletPt
+aDelayedBulAt vfact maycid pos vel drag hiteff width = BulletPt
     { _ptDraw = drawBul
     , _ptUpdate = \w -> resetVel . mvBullet w
     , _btVel' = vfact *.* vel
+    , _btDrag = drag
     , _btColor' = V4 2 2 2 2
     , _btTrail' = [pos]
     , _btPassThrough' = maycid
@@ -65,6 +69,7 @@ aCurveBulAt maycid col pos control targ hiteff width = BulletPt
     { _ptDraw = drawBul
     , _ptUpdate = \w -> mvBullet w . setVel
     , _btVel' = V2 0 0
+    , _btDrag = 1
     , _btColor' = col
     , _btTrail' = [pos]
     , _btPassThrough' = maycid

src/Dodge/Particle/Bullet/Update.hs

@@ -10,23 +10,21 @@ import Dodge.WorldEvent.ThingsHit
 import Geometry
 --import Geometry.Vector3D
 
+import Data.Bifunctor
 import Control.Lens
 {-
 Update for a generic bullet.
 -}
 mvBullet :: World -> Particle -> (World, Maybe Particle)
 mvBullet w bt 
-    | t <= 0 = wAnd Nothing
-    | t <  4 = wAnd $ Just $ bt
-        & btPassThrough' .~ Nothing
-        & btTrail' .~ (p:p:ps)
-        & btTimer' -~ 1                      
---    | otherwise = hiteff bt (thingsHitExceptCr3D' mcr (addZ 20 p) (addZ 20 (p +.+ vel)) w) w
-    | otherwise = hiteff bt (thingsHitExceptCr mcr p (p +.+ vel) w) w
+    | t <= 0 || magV (_btVel' bt) < 1 = wAnd Nothing
+    | otherwise = second (fmap dodrag) $ hiteff bt (thingsHitExceptCr mcr p (p +.+ vel) w) w
   where 
+    dodrag = btVel' %~ (drag *.*)
+    drag = _btDrag bt
     wAnd    = (w,)
     mcr     = _btPassThrough' bt
-    (p:ps)  = _btTrail' bt
+    (p:_)  = _btTrail' bt
     vel     = _btVel' bt
     hiteff  = _btHitEffect' bt
     t       = _btTimer' bt

src/Dodge/Particle/Spark.hs

@@ -25,6 +25,7 @@ colSpark' randDir time col pos baseDir w = w
     spark = BulletPt
         { _ptDraw = drawBul
         , _ptUpdate = mvBullet
+        , _btDrag   = 0.9
         , _btVel' = rotateV dir (V2 5 0)
         , _btColor' = col
         , _btTrail' = [pos]